Compact Compressor

ABSTRACT

A compact compressor comprising a first tubular housing portion; a second tubular housing portion having a first end region open to the first tubular housing portion and a second end region defining a compression chamber and housing a piston; an electric motor carried by the first tubular housing portion; a driving means connecting the piston to the electric motor; a valve plate seated against the second end region of the second tubular housing portion; and an end cover fixed to the second tubular housing portion and acting against the valve plate and providing, internally and through the valve plate, fluid communications between the compression chamber and the suction line and discharge line of a refrigeration circuit to which the compressor is coupled.

FIELD OF THE INVENTION

The present invention refers to a compact compressor for a refrigeration system, to be used particularly for cooling the components of compact electronic appliances.

BACKGROUND OF THE INVENTION

Electronic equipments in general, and particularly computers, have certain electronic components, such as microprocessors and integrated circuits which, in order to work properly, require their temperatures to be maintained within a certain predetermined temperature interval mainly below an upper limit of this temperature interval, besides guaranteeing the maintenance of the operational properties of these electronic components.

Due to the technological advances regarding mainly the processing speed of these electronic components, issues such as overheat and heat dissipation in equipments using such electronic components have been an increasingly limiting factor to an adequate performance of these electronic components and one of the major obstacles in improving such equipments. Traditional refrigeration systems (radiation or convection) do not lead any more to an efficient refrigeration of the most sensible electronic components, neither to an efficient dissipation of the heat generated by the operation of the equipment comprising such electronic components.

The known solutions of refrigeration systems for electronic equipments, which use compressors operating with a refrigerant fluid (similarly to household refrigeration systems, such as refrigerators and air conditioners) also have other inconveniences, related to the operational needs of such compressors, which are usually of the alternating (or reciprocating) piston type, in which the compression of a refrigerant fluid is achieved by means of the reciprocating motion of a piston inside a cylinder. The operation of said compressors require the use of lubricating oil for the parts in relative motion, demanding the provision of a sump of lubricating oil and an oil pumping system, requiring a larger physical space for providing said compressor in the electronic equipment in which it will operate.

Moreover, the known constructions of the art use a suspension means, usually in the form of springs, in the assembly of the compression mechanism, to reduce transmission of vibration generated as consequence of the reciprocating motion of the piston, which also requires an increase in the final dimensions of the housing, thus requiring more physical space in the electronic equipment in which said compressor will be provided. The use of such compressors further results in an increased weight of the electronic equipment in which they are provided. Besides all these drawbacks, the known refrigeration compressors for household use are difficult to install and are not adapted for the operational conditions necessary to the refrigeration of electronic components.

Due to these drawbacks, the industry of electronic equipment have been adopting other solutions for refrigeration, such as those presented in documents U.S. Pat. No. 4,434,625, U.S. Pat. No. 5,365,749, U.S. Pat. No. 6,687,122 and US2005/0123418, which describe refrigeration systems that do not use a compressor with a reciprocating piston.

OBJECTIVES OF THE INVENTION

The present invention has as an object to provide a compact compressor, particularly for use in the refrigeration of electronic systems, said compressor being of the type using the operational principle of the reciprocating compressors used in household refrigeration, but not presenting the drawbacks known in the art for such compressors when designed to the refrigeration of a small size electronic equipment.

It is a further object of the present invention to provide a compressor such as mentioned above, which does not require the use of liquid lubricating fluids for the parts in relative motion.

It is a further object of the present invention to provide a compressor which, besides the features above, has reduced dimensions, low weight and allows an easy assembly and replacement thereof in small size electronic equipments.

It is also one of the objects of the present invention to provide a compressor with a reciprocating piston, such as mentioned above, and presenting the least vibration possible.

It is a further object of the present invention to provide a compressor of the type mentioned above, which presents a compression mechanism that does not demand a suspension system of the type known in the art.

SUMMARY OF THE INVENTION

The objectives mentioned above are achieved by the provision of a compact compressor for refrigeration of several systems, such as electronic systems, comprising: a first tubular housing portion having a first end carrying a motor cover, and a second open end; a second tubular housing portion having a first end region open to the second end of the first tubular housing portion and a second end region defining a compression chamber; a piston located inside the compression chamber defined inside the second tubular housing portion; an electric motor fixed in the first tubular housing portion; a piston driving means, connecting the electric motor to said piston, so that the former drives the latter in reciprocating motions inside the compression chamber; a valve plate seated against the second end region of the second tubular housing portion, closing one end of the compression chamber; an end cover fixed to the second tubular housing portion and acting against the valve plate in order to retain the latter hermetically seated against the second end region of the second tubular housing portion, said end cover providing, internally and through the valve plate, fluid communications between the compression chamber and respective discharge and suction lines of a refrigeration circuit to which the compressor is coupled.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the attached drawings, in which:

FIG. 1 represents a schematic front view of the compressor of the present invention;

FIG. 2 represents a schematic upper view of the compressor illustrated in FIG. 1;

FIG. 3 represents a schematic lateral view of the compressor illustrated in FIG. 1;

FIG. 4 represents a schematic longitudinal cross-sectional view of the compressor illustrated in FIG. 1;

FIG. 5 represents a schematic exploded perspective view of the compressor illustrated in FIG. 4;

FIG. 6 represents an enlarged schematic longitudinal cross-sectional view of the top region of the cylinder, with the piston being in an intermediate position of its compression cycle;

FIG. 7 represents a schematic front view of an alternative construction for the compressor illustrated in FIG. 1; and

FIG. 8 represents a schematic longitudinal cross-sectional view of the compressor construction illustrated in FIG. 7;

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

The present invention presents a compact compressor used particularly, although not exclusively, for the refrigeration of electronic systems, said compact compressor generally comprising a first tubular housing portion 10 and a second tubular housing portion 20, for example defining together a single piece body, said second tubular housing portion 20 lodging a piston 30 reciprocating inside a compression chamber C defined inside said second tubular housing portion 20, the first tubular housing portion 10 carrying an electric motor 40 for driving said piston 30 in strokes of suction and compression of a refrigerant gas of a refrigeration system to which the compact compressor of the present invention is coupled. Piston 30 is driven by the electric motor 40 through a driving means 50 connected to the parts of piston 30 and electric motor 40, as described ahead, so that the latter drives the piston 30 in reciprocating motion inside the compression chamber C. The present invention comprises a compressor in which the parts moving in relation to each other are built in order to eliminate the need of providing lubricating oil in the compressor, as well as a sump for said oil and means for pumping said oil to the moving parts.

In a constructive option of the present invention, the parts of the compressor with relative motion are built of self-lubricating material such as, for example, some plastics. In another constructive option of the present invention, said parts with relative motion are made of anti-friction material, or provided with an anti-wear low friction coating.

In a way of carrying out the present invention, the piston 30 is produced of self-lubricating material such as, for example, some engineering plastics or conventional material covered by anti-wear low friction surface coatings such as, for example, the compression chamber C, inside which piston 30 moves, which may also receive an outer sleeve with a coating as mentioned above.

Besides reducing friction between the relatively moving parts, the selection of the material that forms the elements of the compressor of the present invention considers questions of balancing in the compressor. Within this concept, the compact compressor being described preferably presents its elements formed of low mass density materials, in order to reduce unbalancing loads generated by the reciprocating motion of piston 30. The compressor built according to the present invention may be used in a wide range of rotations, for example from 3,000 to 15,000 rpm, due to the characteristics thereof.

The first tubular housing portion 10 has a first end 11, carrying a motor cover 60, and a second end 12, open to the interior of the second tubular housing portion 20, which presents a first end region 21, open to the second end 12 of the first tubular housing portion 10, and a second end region 22, defining a compression chamber C.

In the illustrated embodiments, the second tubular housing portion 20 defines a cylinder inside which is mounted piston 30 between the suction and compression strokes thereof. However, it should be understood that other constructions are possible, such as the second tubular housing portion 20 carrying a tubular sleeve, for example, of anti-friction material, fixed inside a longitudinal extension of the second tubular housing portion 20 and internally defining the compression chamber C, as described above.

A valve plate 70, in which are defined a suction orifice 71 and a discharge orifice 72 which are selectively closed by a respective suction valve 73 and a respective discharge valve 74, is seated against the second end region 22 of the second tubular housing portion 20, closing one end of the compression chamber C opposite to that and through which the piston 30 is mounted.

The compressor of the present invention further comprises an end cover 80 fixed to the second tubular housing portion 20 and acting against the valve plate 70, in order to retain the latter hermetically seated against the second end region 22 of the second tubular housing portion 20, said end cover 80 providing, internally and through the valve plate 70, fluid communications between the compression chamber C and a suction line 1 and a discharge line 2, respectively, of a refrigeration circuit (not illustrated) to which the compressor is coupled.

According to the present invention, the fluid communication between the compression chamber C and the suction line 1 is defined by means of a connecting means 81 in the shape of a passage provided inside the end cover 80 and lodging an adjacent end of the suction line 1. The fluid communication between the compression chamber C and the discharge line 2 is defined by a discharge chamber 82 provided inside the end cover 80, and which receives the refrigerant gas compressed in compression chamber C to be fed to the refrigeration system to which the present compressor is coupled through the discharge line 2.

According to the present invention, the end cover 80 is fixed around at least part and, for example, the entire longitudinal extension of the second tubular housing portion 20 surrounding the valve plate 70, said fixation being effected, for example, by gluing or by mechanical interference, such as by the actuation of an internal thread 83 provided in the end cover 80, to be engaged to an outer thread 23 provided in the second end region 22 of the second tubular housing portion 20.

While the embodiments illustrated herein present a fluid communication between the compression chamber C and the suction line 1 through a connecting means 81, it should be understood that the present invention also applies to constructions with fluid communication between the suction line 1 and the compression chamber C through a suction chamber provided in the end cover 80 or in a cover internal to the latter, such as described below.

The supply of refrigerant gas through the connecting means 81 is carried out directly and hermetically to the interior of the compression chamber C of the compression cylinder, through the suction valve 73, establishing an operational pressure with an intermediate value between the suction and discharge pressures inside a cavity 20 a defined in the second tubular housing portion 20. This construction results in a smaller pressure difference through piston 30 and therefore in smaller loads on the bearings due to compression. Further, this construction minimizes gas leaks to the interior of said cavity 20 a, through the gap between piston 30 and the cylinder of the second tubular housing portion 20, when in a stable operation, increasing the energetic yield of the compressor and allowing the use of larger diametral gaps between the piston 30 and the cylinder than those used in conventional compressors.

The discharge chamber 82 is designed to maximize the use of its internal volume for dampening the refrigerant gas pulsation generated by the operation of the compressor, and separate the existing discharge volume from the suction line 1. In a constructive option, this construction further provides the fixation of the discharge valve system.

According to the illustrations in FIGS. 1 to 5, the end cover 80 is built in a single piece, being internally provided with the connecting means 81 and the discharge chamber 82. However, other constructions are possible within the concept presented herein, as illustrated in FIGS. 6 and 8, in which a cylinder cover 90, internal to the end cover 80, is seated against the valve plate 70, as described below, said cylinder cover 90 being, for example, partially or totally surrounded by the end cover 80. In this construction, the cylinder cover internally defines a connecting means 91, for fluid communication between the compression chamber C and the suction line 1, and a discharge chamber 92, which receives the gas compressed in compression chamber C and the discharge line 2.

In this construction, in order to maintain the seating conditions of the parts of cylinder cover 90 and valve plate 70 against the second end region 22 of the second tubular housing portion 20, the end cover 80 is pressed and welded to the second tubular housing portion 20, as illustrated in FIG. 6.

The fixation of the end cover 80 to the second tubular housing portion 20 results in an improved hermeticity of the compressor, further allowing a reduction of the dimensions thereof since it eliminates the flange portions for mutual seating of parts fixed to each other by means of bolts, rivets, etc.

According to the present invention, the maintenance of the seal between the suction and discharge sides, defined in the end cover 80 or in the cylinder cover 90, during operation, is guaranteed by the provision of sealing joints 25. Alignment pins 26 are used to ensure the positioning of the components that comprise the closure of the second end 22 of the second tubular housing portion 20 and which define the head of the compressor. A sealing joint 25 is applied between the end portion 22 of the second tubular housing portion 20 and the suction valve 73, in order to achieve the adjustment of minimum compression chamber and to limit the unwanted volume present in compression chamber C. In the illustrated embodiments, the first tubular housing portion 10 is defined orthogonally to the second tubular housing portion 20, with the driving means 50 comprising a crankshaft 51 having an eccentric end portion 52 projecting to the interior of the second tubular housing portion 20 and a basic portion 53 projecting to the interior of the first tubular housing portion 10, the electric motor 40 being fixed to said basic portion 53 of the crankshaft 51.

In the embodiment illustrated in FIGS. 1 to 5, the electric motor comprises: an internal element, or rotor 41, which effects the rotation motion and which is fixed directly to the basic portion 53 of the crankshaft 51; and an external element, or stator 42, which is fixed to the first tubular housing portion 10, which is elongated. In this construction, the motor cover 60 is fixed to the first end 11 of the first portion of the tubular housing 10.

In the constructive option illustrated in FIGS. 7 and 8, the electric motor 40 is fixed to the basic portion 53 of the crankshaft 51 by means of the telescopic mounting of a motor shaft portion 40 a internally to the basic portion 53 of the crankshaft 51. In this construction, the motor cover 60 is fixed to an end portion of said electric motor 40 which is opposite to that of fixation of the motor shaft 40 a to the crankshaft 51. For this construction, the first tubular housing portion 10 carries a tubular sleeve 15 mounted around the first end 11, in order to surround an adjacent end portion of the electric motor 40, securing the latter to said first tubular housing portion 10.

According to one way of carrying out the present invention, the crankshaft 51 comprises, in a single piece, the eccentric end portion 52 and the basic portion 53, which extends for at least along the first tubular housing portion 10 in the mounting region of the electric motor 40.

In another way of carrying out the invention, the crankshaft 51 is formed by two or more parts coupled to each other, with one of said parts being defined by the eccentric end portion 52 and the other, the basic portion 53, coupled and fixed, by appropriate means, such as interference, glue, etc., to said eccentric end portion 52.

According to the illustrations of FIGS. 4 and 5, the eccentric end portion 52 presents a tubular free end that telescopically houses an adjacent end of the basic portion 53 of the crankshaft 51.

The driving means 50 further comprises a connecting rod 55 connecting the piston 30 to the electric motor 40, said connecting rod 55 having a smaller eye 55 a mounted inside piston 30 and a larger eye 55 b mounted to the eccentric end portion 52 of the crankshaft 51.

In this construction, the smaller eye 55 a is mounted around an articulation pin 31 located inside piston 30 by means of a hole 32 provided thereon, said articulation pin 31 of piston 30 being built so as to be pressed into the smaller eye 55 a of the connecting rod 55, with a controlled diametral gap of the holes 32 of piston 30. The self-lubricating feature of piston 30 is used to reduce friction between the articulation pin 31 and the hole 32, avoiding wear between these parts.

According to the present invention, the compact compressor being described also comprises a pair of rolling bearings 100 mounted axially spaced from each other inside the first tubular housing portion 10 and bearing the crankshaft 51.

The maintenance of the assembly condition of the eccentric end portion 52 of the crankshaft 51 is obtained through the insertion of the bearing units 100, crankshaft 51 and electric motor 40, simultaneously and coaxially to the axis of the first tubular housing portion 10, holding in position the connecting rod 55, piston 30 and articulation pin 31 of piston 30 assembly, with an auxiliary rolling bearing 110 previously mounted to the larger eye 55 b of the connecting rod 55.

In the construction illustrated in FIGS. 7 and 8, the crankshaft 51 has the eccentric end portion 52 thereof supported by one of the rolling bearings 100, through a counterweight 56 provided inferiorly to said eccentric end portion 52 of the crankshaft 51. In order to maintain the assembly balance of the crankshaft 51, the other rolling bearing 100 of the pair of rolling bearings 100 is mounted around a tubular free end portion of the eccentric end portion 52 and which telescopically couples an adjacent end of a motor shaft 40 a of the electric motor 40, said electric motor 40 carrying, in a respective end 42 spaced from the motor shaft 40 a, a motor cover 60. To facilitate the assembly of the piston 30, of its driving means and of the electric motor 40, the second tubular housing portion 20 of the present invention has an end opening 24, defined in its first end region 21 and which is closed by an additional cover 26, preferably welded to the first end portion 21 of the tubular portion 20.

According to the present invention, at least one of the parts of first tubular housing portion 10 and end cover 80 is externally provided with heat exchange fins 120, which allow the cooling of the present compressor during operation. In the illustrated embodiment, the parts of first tubular housing portion 10 and second tubular housing portion 20 are provided with heat exchange fins, allowing the release of the heat generated by the motor and by the compression of refrigerant fluid in the compression chamber C to the outside of the compressor.

In a way of carrying out the present invention, the heat exchange fins 120 provided in the first tubular housing portion 10 are circumferential and the heat exchange fins 120 provided in the end cover 80 are longitudinal.

The heat exchange fins 120 are defined by grooves 13, 27 respectively provided on the first and second portions of tubular housing 10, 20, dimensioned so as not to interfere in the circumferential dimensioning of said housing portion. 

1. A compact compressor, wherein it comprises: a first tubular housing portion having a first end carrying a motor cover, and a open second end; a second tubular housing portion having a first end region open to the second end of the first tubular housing portion and a second end region defining a compression chamber; a piston located inside the compression chamber defined inside the second tubular housing portion; an electric motor fixed in the first tubular housing portion; a driving means of the piston, connecting the electric motor to said piston, so that said electric motor drives said piston in reciprocating motion inside the compression chamber; a valve plate seated against the second end region of the second tubular housing portion, closing one end of the compression chamber; an end cover fixed to the second tubular housing portion and acting against the valve plate in order to hold the latter hermetically seated against the second end region of the second tubular housing portion, said end cover providing, internally and through the valve plate, fluid communications between the compression chamber and respective suction line and discharge line of a refrigeration circuit to which the compressor is coupled.
 2. Compressor, according to claim 1, wherein the end cover is fixed around at least part of the longitudinal extension of the second tubular housing portion, surrounding the valve plate.
 3. Compressor, according to claim 2, wherein the end cover is fixed by mechanical interference around the second tubular housing portion.
 4. Compressor, according to claim 3, wherein the end cover is provided with an inner thread to be engaged to an outer thread provided in the second tubular housing portion.
 5. Compressor, according to claim 1, wherein the fluid communication between the compression chamber and the discharge line is defined by a discharge chamber provided inside the end cover.
 6. Compressor, according to claim 1, wherein the fluid communication between the compression chamber and the suction line is defined by a connecting means formed inside the end cover and housing an adjacent end of the suction line.
 7. Compressor, according to claim 1, wherein it comprises a cylinder cover located between the valve plate and the end cover, the latter acting against the valve plate through the cylinder cover.
 8. Compressor, according to claim 7, wherein the cylinder cover is surrounded by the end cover.
 9. Compressor, according to claim 7, wherein the fluid communication between the compression chamber and the discharge line is defined by a discharge chamber formed inside the cylinder cover.
 10. Compressor, according to claim 7, wherein the fluid communication between the compression chamber and the suction line is defined by a connecting means to an adjacent end of the suction line, formed inside the cylinder cover.
 11. Compressor, according to claim 1, wherein the compression chamber is laterally and circumferentially defined by a tubular sleeve made of an anti-friction material fixed inside the second end region of the second tubular housing portion.
 12. Compressor, according to claim 1, wherein the piston is made of a self-lubricating material.
 13. Compressor, according to claim 1, wherein the second tubular housing portion is orthogonal to the first tubular housing portion.
 14. Compressor, according to claim 13, wherein the driving means comprises a connecting rod connecting the piston to the electric motor.
 15. Compressor, according to claim 14, wherein it comprises: —a pair of rolling bearings mounted axially spaced to each other inside the first tubular housing portion; —a crankshaft mounted to the pair of rolling bearings and having an eccentric end portion projecting to the interior of the second tubular housing portion and to which is connected the connecting rod and a basic portion projecting to the interior of the first tubular housing portion, the electric motor being fixed to said basic portion of the crankshaft by the first tubular housing portion.
 16. Compressor, according to claim 15, wherein the crankshaft comprises a counterweight provided in the region of the eccentric end portion of said crankshaft.
 17. Compressor, according to claim 16, wherein the eccentric end portion and basic portion of the crankshaft are made of separate parts which are fixed to each other.
 18. Compressor, according to claim 17, wherein the eccentric end portion of the crankshaft is telescopically mounted and fixed to an adjacent end of the basic portion of said shaft.
 19. Compressor, according to claim 1, wherein the first tubular housing portion is elongated and internally secures, along its length a stator of the electric motor, the crankshaft extending along the entire length of the first tubular housing portion and carries a rotor of the electric motor.
 20. Compressor, according to claim 19, wherein the motor cover is fixed to the first end of the first tubular housing portion.
 21. Compressor, according to claim 19, wherein at least one of the parts of first tubular housing portion and end cover is externally provided with heat exchange fins.
 22. Compressor, according to claim 21, wherein the heat exchange fins provided in the first tubular housing portion are circumferential.
 23. Compressor, according to claim 22, wherein the heat exchange fins provided in the end cover are longitudinal.
 24. Compressor, according to claim 1, wherein the second tubular housing portion has an end opening provided in its first end region and closed by an additional cover.
 25. Compressor, according to claim 15, wherein the electric motor is mounted to the first end of the first tubular housing portion and carries, in a respective end spaced therefrom, the motor cover. 